Biomedical subjects
Publications and source records attributed to S D Miron.
Presented is a case in which there was significant accumulation of In-111 Octreotide in brain infarcts. It is likely that the accumulation was nonspecific and due to breakdown of the blood-brain barrier.
Geometric measurements of the left ventricular diameters as used in biplane angiocardiography and echocardiography were applied to gated SPECT Tc-99m sestamibi myocardial scintigrams in order to calculate the left ventricular ejection fraction. These measurements take no longer than 5 minutes and require no additional computer software. In a review of 79 examinations, the left ventricular ejection fraction calculated using these measurements correlated well with the echocardiographically estimated ejection fraction (r = 0.78, P < 0.0001). The technique is highly reproducible with an intraobserver correlation of r = 0.94 and interobserver correlation of r = 0.93.
Technetium-99m-sestamibi (MIBI) is a new radionuclide for imaging parathyroid tissue. The purpose of this study was to evaluate parathyroid localization using single radiotracer, dual-phase MIBI scintigraphy and to compare the results to ultrasonography. Twenty-one patients with hyperparathyroidism underwent dual-phase scintigraphy using 25 mCi MIBI and high resolution ultrasonography before parathyroidectomy. Scan results were correlated with size, weight, location, and histopathology of excised parathyroid glands, thyroid abnormalities, and cost. Seventeen patients were female, five had secondary or tertiary hyperparathyroidism, and three had a previous parathyroid exploration. Twenty patients (95%) were cured, 14 with a single and 1 with a double adenoma, and 5 of 6 patients with generalized hyperplasia. There were no false positive MIBI scans and one false positive ultrasound study, despite associated thyroid nodules in 29 per cent of patients. The sensitivity of MIBI and ultrasound in the identification of adenomas was 87 per cent versus 57 per cent (P = 0.046), and the rate of detection of hyperplastic glands was 44 per cent versus 24 per cent (P = 0.19), respectively. There was no correlation between scan results and size, weight, or location of adenomatous glands. The cost of dual-phase MIBI was comparable to that of ultrasound. Dual-phase MIBI is more sensitive than ultrasound in the localization of adenomas and is the preferable modality for preoperative parathyroid localization. Neither MIBI nor ultrasound is effective in localization of hyperplastic glands, underscoring the importance of routine bilateral neck exploration.
To evaluate whether a prolonged infusion of Tc-99m sestamibi allows for visualization of viable myocardium in areas of hypoperfused myocardium, 25 patients were prospectively studied. Each patient was imaged four times in two consecutive days in the following manner: day 1:1) immediately after injection of Tl-201 at rest, 2) 1 hour after a bolus injection of Tc-99m sestamibi at rest; and day 2: 1) imaging in the Tl-201 window for 24 hour redistribution, 2) imaging after a 1-hour infusion of Tc-99m sestamibi. The two Tc-99m sestamibi and two Tl-201 studies were evaluated for presence of redistribution. This was present both on the Tl-201 and Tc-99m sestamibi studies (concordant) in 13 cases, and absent on both the Tl-201 and Tc-99m sestamibi studies (concordant) in 9 cases. In two cases redistribution was seen on the Tl-201 images only, and in one case it was seen on the Tc-99m sestamibi images only (discordant). Tc-99m sestamibi infusion may provide information about the presence of viable myocardium which is similar to that provided by Tl-201 24-hour imaging.
In nuclear medicine, artifacts may simulate a pathologic process; their recognition is therefore necessary to avoid misdiagnosis. Artifacts may be divided into three groups: 1) camera dependent artifacts; 2) radiopharmaceutical dependent artifacts; and 3) patient-related artifacts. The authors present a variety of artifacts and discusses their possible prevention.
The exercise-induced changes in left ventricular filling in patients with coronary artery disease are poorly understood. Therefore these changes were studied in relation to a noninvasive indicator of exercise pulmonary venous congestion, the lung-to-heart (L:H) ratio on symptom-limited thallium stress testing. Fifty-six patients undergoing diagnostic treadmill testing were studied; 50 of them had technically adequate Doppler recordings and became the subjects of this study. Doppler left ventricular filling was assessed with patients in the supine position both before and after exercise. Measurements included early (E) and late (A) filling velocities, their ratio, the diastolic time-velocity integral, and the diastolic filling time. The L:H ratio was considered abnormal if it was greater than the upper 95% confidence limit for a separate group of normal subjects. Twelve subjects had a documented prior myocardial infarction, 16 had stress-induced ischemia, and 20 had abnormal L:H ratios. A greater E and a longer diastolic filling time in the group with an abnormal L:H ratio were the only postexercise measurements that differed; however, E was the only filling parameter that both differed between groups after exercise (abnormal L:H group 87 +/- 25 cm/sec; normal 68 +/- 20 cm/sec; p < 0.01) and whose change from rest to after exercise was significantly different (p < 0.05). Since Doppler velocities are directly related to instantaneous gradients, the higher E in patients with evidence of exercise pulmonary congestion suggests a higher exercise early diastolic left atrial pressure.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
A simple technique is described for generating ventilation/perfusion ratio and perfusion/ventilation ratio images from the posterior Tc-99m PYP aerosol inhalation and Tc-99m MAA perfusion images obtained during routine lung scintigraphy. These images highlight areas of ventilation/perfusion incongruence--mismatch or reverse mismatch--that may sometimes be difficult to detect on conventional images.
Urinary tract abnormalities are detected as incidental findings in 15% of skeletal scintigraphic studies. Several scintigraphic patterns denote these abnormalities. Bilateral diffuse increased uptake is found in patients who have undergone chemotherapy and those with hyperparathyroidism, hypercalcemia, and sickle cell disease. Bilateral diffuse decreased uptake occurs in patients with end-stage renal disease, extensive metastatic disease to the bone, and various hematologic disorders. Focal increased activity is associated with postoperative changes and effects from radiation therapy. Focal decreased uptake is caused by space-occupying lesions such as abscesses, cysts, and neoplasms. Abnormal size, shape, and position associated with abnormalities of the kidney and bladder can also be seen. Although these scintigraphic patterns are seldom suggestive of a definitive diagnosis, they are highly specific for urinary tract disease.
Scintigraphic studies of the oropharyngeal transit of a liquid bolus were performed in 15 healthy controls, 12 patients with symptoms of oral-pharyngeal dysphagia, and 13 patients with neuromuscular disease, who did not have dysphagia. Gamma camera imaging of the head, neck, and upper thorax was undertaken, in the lateral projection, during the swallowing of the radiolabeled bolus of water. Inspection of summed images permitted the selection of regions of interest (ROI) to represent the mouth, pharynx, and upper esophagus. Transit times between each ROI were calculated and compared. Significant prolongation of bolus transit time between the mouth and esophagus was present in both patients with and without dysphagia (0.59 +/- 0.38 sec and 0.33 +/- 0.7 sec; mean +/- SD, respectively) compared with controls (0.26 +/- 0.04 sec P less than 0.001, P less than 0.01, respectively, Mann-Whitney U test). Repeat studies in 25 individuals indicated that the transit measurements were more reproducible between swallows in normal subjects than in patients with symptoms. Deglutitive scintigraphy provides a noninvasive technique for the quantitative study of swallowing and its disorders.
Bone scintigrams are usually obtained for evaluation of skeletal abnormalities; soft-tissue abnormalities are often an unexpected finding. However, the recognition of specific conditions with extraskeletal accumulation of bone-seeking radiopharmaceuticals greatly enhances the diagnostic value of the study. Several examples of abnormal nonosseous uptake in both neoplastic and nonneoplastic processes involving the brain, lung, heart, breast, bowel, liver, spleen, skeletal muscle, kidney, and bladder are presented. Examples of artifactual uptake in the soft tissues are also described. Causes for nonosseous accumulation are discussed.
The ST segment shift relative to exercise-induced increments in heart rate, the ST/heart rate slope (ST/HR slope), has been proposed as a more accurate ECG criterion for diagnosing significant coronary artery disease (CAD). Its clinical utility, with the use of a standard treadmill protocol, was compared with quantitative stress thallium (TI) and standard treadmill criteria in 64 unselected patients who underwent coronary angiography. The overall diagnostic accuracy of the ST/HR slope was an improvement over TI and conventional ST criteria (81%, 67%, and 69%). For patients failing to reach 85% of their age-predicted maximal heart rate, its diagnostic accuracy was comparable with TI (77% and 74%). Its sensitivity in patients without prior myocardial infarctions was equivalent to that of thallium (91% and 95%). The ST/HR slope was directly related to the angiographic severity (Gensini score) of CAD in patients without a prior infarction (r = 0.61, p less than 0.001). The ST/HR slope was an improved ECG criterion for diagnosing CAD and compared favorably with TI imaging.
We determined quantitatively the amount of sodium morrhuate that reaches the pulmonary vascular bed during endoscopic variceal sclerotherapy to ascertain whether this affects the diffusing capacity of the lung to carbon monoxide (DLCO). Eleven patients had measurements of DLCO and specific diffusing capacity (DLCO/VA) before and after sclerotherapy. In ten of these patients sclerotherapy was done using sodium morrhuate mixed with 99mTc-labeled albumin microspheres followed by quantitative radionuclide scanning. Most of the sodium morrhuate, 80 +/- 18% (SD) of the total dose, remained in the region of the esophagus. Only 20% of the injected dose reached the pulmonary circulation. There were no changes in DLCO or DLCO/VA. We conclude that most of the sclerosing solution injected during endoscopic variceal sclerotherapy remains at the site of injection. As a result, the pulmonary endothelium is exposed to small amounts of sodium morrhuate and no change in diffusing capacity occurs.
Discrepant enhancement of an internal jugular vein on computed tomography during intravenous infusion of contrast material via an upper extremity vein constitutes an abnormal finding. We demonstrate that the greater degree of opacification of the internal jugular vein on the affected side is due to reversal of flow on that side and is indicative of occlusion of a major venous pathway proximally.
We describe a manually operated system, simple to assemble, that will enable xenon-133 lung ventilation studies to be performed on ventilator-assisted patients. It can be constructed from items readily available. Radiation exposure levels to the operator were measured and are reported.